The enhancement of TiO₂photocatalytic activity by hydrogen thermal treatment

Abstract

In this study, conventional TiO₂powder was heated in hydrogen (H₂) gas at a high temperature as pretreatment. The photoactivity of the treated TiO₂samples was evaluated in the photodegradation of sulfosalicylic acid (SSA) in aqueous suspension. The experimental results demonstrated that the photodegradation rates of SSA were significantly enhanced by using the H₂-treated TiO₂catalysts and an optimum temperature for the H₂treatment was found to be of 500–600°C. The in situ electron paramagnetic resonance (EPR) signal intensity of oxygen vacancies (OV) and trivalent titanium (Ti³⁺) associated with the photocatalytic activity was studied. The results proved the presence of OV and Ti³⁺ in the lattice of the H₂-treated TiO₂and indicated that both were contributed to the enhancement of photocatalytic activity. Moreover, the experimental results presented that the EPR signal intensity of OV and Ti³⁺ in the H₂-treated TiO₂samples after 10 months storage was still significant higher than that in the untreated TiO₂catalyst. The experiment also demonstrated that the significant enhancement occurred in the photodegradation of phenol using the H₂-treated TiO₂.